Definition
Common meter is a pattern of alternating line lengths: an eight-syllable line (four stresses) followed by a six-syllable line (three stresses), repeated in four-line stanzas. In metrical terms, this is iambic tetrameter alternating with iambic trimeter. The pattern is typically noted as 8-6-8-6 and abbreviated as CM in hymnal notation.
It feels familiar because you’ve heard it throughout your life. This meter is used in hundreds of Protestant hymns, including "Amazing Grace" and "O God, Our Help in Ages Past." It’s also the meter that Emily Dickinson favored in most of her poems. Since this pattern is so ingrained in English-speaking culture, when a poet employs it, they trigger a kind of background hum in the reader—something that feels like a blend of a hymn and a nursery rhyme, both solemn and singable.
This duality is precisely why poets are drawn to it. The six-syllable lines create a slight pause, a breath, a sense of incompleteness that the subsequent eight-syllable line resolves. The rhythm propels the reader forward effortlessly. It can convey grief, joy, irony, or straightforward statements, all while feeling as natural as a heartbeat. When a poet disrupts it—by dropping a stress or stretching a line—the reader senses the shift immediately, giving the poet a precise emotional tool to engage with.